1. Field
The embodiments relate to a communication protocol conversion in a communication circuit, and a conversion method for a bus protocol at the time of a data transfer using a bus.
2. Description of the Related Art
In recent years, a software wireless device (SDR: Software Defined Radio) has been put into practical use. This software wireless device is a wireless device that can absorb differences in communication methods by dynamically changing a circuit configuration with the use of a reconfigurable logic such as a field programmable gate array (FPGA) in order to support, for example, communication methods of various types of cellular phones with one device.
FIG. 1 is a block diagram showing the configuration of such a software wireless device. In this device, digital data accessed by an MAC (Media Access Controller) 105 within a digital BB (Base Band) unit 100 is encoded and modulated by a physical layer processing unit (PHY) 106, D/A converted by an analog BB unit 101, and transmitted from an antenna 103 via an analog RF (Radio Frequency) unit 102, at the time of transmission. A wireless signal received by the antenna 103 is A/D converted by the analog BB unit 101 via the analog RF unit 102, synchronized, demodulated, error-corrected, etc. by the physical layer processing unit 106, and transferred to media on a receiving side by the media access controller 105.
In such a software wireless device, especially, a circuit that constitutes the physical layer processing unit 106 within the digital BB unit 100 is dynamically changed by using a reconfigurable circuit in correspondence with various types of communications methods, whereby one wireless device can support, for example, methods of various types of cellular phones.
FIG. 2 is a schematic explaining a network (bus) connection for various types of digital processes within the physical layer processing unit 106 using this reconfigurable circuit. For example, data from a circuit on the left side not shown is input to any of reconfigurable circuits 109a to 109d via any of selectors 108a to 108d depending on need. For example, the reconfigurable circuit 109a is a circuit that can support a plurality of modulation methods, and its configuration can be dynamically changed in correspondence with a communication method such as BPSK (Binary Phase Shift Keying), QPSK (Quadrature Phase Shift Keying), etc. Additionally, for example, the reconfigurable circuit 109b is, for example, a circuit for an error correction, and its configuration can be dynamically changed in correspondence with various methods of error corrections. Communication data is digitally processed by some of these reconfigurable circuits depending on need, and passed to the analog BB unit 101, for example, as transmission data.
FIG. 3 is a schematic explaining a conventional example of a protocol conversion method in such a software wireless device, etc. In this figure, if data is transferred from a preceding stage circuit 111, namely, the circuit not shown on the left side of a network in the description of FIG. 2 to a succeeding stage circuit 112, for example, the reconfigurable circuit 109a, a protocol conversion circuit that copes with a communication protocol dynamically changed in accordance with the succeeding stage circuit 112, namely, the reconfigurable circuit 109a is required. In FIG. 3, 3 protocol conversion circuits 115a to 115c correspond to this required protocol conversion circuit. Conventionally, it is necessary to feed any of the outputs of the 3 protocol conversion circuits 115a to 115c to the succeeding stage circuit 112 via a selector 114 in accordance with a dynamic change in a protocol on the side of the succeeding stage circuit 112.
Such a conventional technique has problems such that a plurality of bus protocol conversion circuits are required in correspondence with a change in a circuit configuration corresponding to the communication method of the succeeding stage circuit, and information required for a protocol conversion must be obtained from the side of the succeeding stage circuit 112. For example, information indicating that a longer time is required to process data on the side of the succeeding stage circuit 112 than that in the preceding stage circuit 111 may be required for the protocol conversion. As a result, the above-mentioned conventional technique also has a problem such that a control for obtaining the information becomes complicated when such information dynamically changes.
As a conventional technique related to such a protocol conversion circuit, the following document exists. Patent Document 1: Japanese Published Unexamined Patent Application No. H6-332847 “Bus Conversion And Connection Circuit”
Aforementioned document discloses a device that connects 2 buses in different forms, and also discloses a technique for transmitting, from the side of a preceding stage circuit to a conversion circuit, data having a format where parameters for a conversion circuit, which correspond to the protocol of the side of the succeeding stage circuit, are attached to the header of a frame.